Over time, wind turbines may begin to experience vibrations. Vibrations may be the result of an aerodynamic imbalance caused by misalignment of the blades of the turbine rotor or a mass imbalance in the rotor, inclusive of the hub and blades. The vibrations may also be caused by improper alignment of the rotor at the time of installation, or after a major repair or replacement any of the rotor components. Vibrations may cause accelerated wear of gear boxes, bearings, rotor blades and possibly other components which result in reduced operating efficiency and electrical power production. Depending on the cause and/or magnitude of the vibrations, and the extent of the damage to the wind turbine, repairs may be required. In extreme cases, the wind turbine may collapse if the vibrations become too large. The vibrations may also increase the sound generated by the wind turbine during operation, which may be a cause of noise pollution, particularly when the wind turbine is located in or near a residential neighbourhood.
Thus, it is desirable to have a method of detecting aerodynamic imbalances and/or mass imbalances in a wind turbine rotor.